In the easy to use advertising system, anyone setting up a Facebook advertising campaign can target employees of any organisation, and type in any kind of interest they want to target. That could be kittens and cupcakes, or it could be kinky sex, Barely Legal magazine or the Tory party.

The ad system can dig into private details that Facebook users had no intention of sharing outside their chosen "friends" to show these preferences.

The flaws outing have major implications for employee privacy.

For instance, the RSPB could use it to dig out employees or volunteers who secretly like barbecued chicken. Coke could determine whether traitorous staff like Pepsi. Or the BNP could use it to dig out members who actually kinda like everyone.

The youngster had made sure not to reveal his personal details for his own reasons, but his Facebook page was plastered with ads targeted at gay people.

This new privacy issue is not something you can do anything about either.

Facebook's ad system allows advertisers to target their advertising campaign to those with very specific interests, and the ads are particularly easy to set up, and open to anyone with a Facebook account.

What inconvenient or harmful Facebook ads have turned up on your page? Has your boss used Facebook to spy on you?